selftests/ftrace: Check required filter files before running test

Without CONFIG_DYNAMIC_FTRACE, some tests get failure because required
filter files(set_ftrace_filter/available_filter_functions/stack_trace_filter)
are missing. So implement check_filter_file() and make all related tests
check required filter files by it.

BTW: set_ftrace_filter and available_filter_functions are introduced together
so just check either of them.

Signed-off-by: Xiao Yang <[e-mail]>
Acked-by: Masami Hiramatsu <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter-stack.tc

···
     exit_unsupported
 fi
 
-if [ ! -f set_ftrace_filter ]; then
-    echo "set_ftrace_filter not found? Is dynamic ftrace not set?"
-    exit_unsupported
-fi
+check_filter_file set_ftrace_filter
 
 do_reset() {
     if [ -e /proc/sys/kernel/stack_tracer_enabled ]; then

tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter.tc

···
     exit_unsupported
 fi
 
+check_filter_file set_ftrace_filter
+
 fail() { # msg
     echo $1
     exit_fail

tools/testing/selftests/ftrace/test.d/ftrace/func-filter-glob.tc

···
     exit_unsupported
 fi
 
+check_filter_file set_ftrace_filter
+
 disable_tracing
 clear_trace
 

tools/testing/selftests/ftrace/test.d/ftrace/func-filter-notrace-pid.tc

···
     exit_unsupported
 fi
 
-if [ ! -f set_ftrace_filter ]; then
-    echo "set_ftrace_filter not found? Is function tracer not set?"
-    exit_unsupported
-fi
+check_filter_file set_ftrace_filter
 
 do_function_fork=1
 

tools/testing/selftests/ftrace/test.d/ftrace/func-filter-pid.tc

···
     exit_unsupported
 fi
 
-if [ ! -f set_ftrace_filter ]; then
-    echo "set_ftrace_filter not found? Is function tracer not set?"
-    exit_unsupported
-fi
+check_filter_file set_ftrace_filter
 
 do_function_fork=1
 

tools/testing/selftests/ftrace/test.d/ftrace/func-filter-stacktrace.tc

···
 # description: ftrace - stacktrace filter command
 # flags: instance
 
-[ ! -f set_ftrace_filter ] && exit_unsupported
+check_filter_file set_ftrace_filter
 
 echo _do_fork:stacktrace >> set_ftrace_filter
 

tools/testing/selftests/ftrace/test.d/ftrace/func_event_triggers.tc

···
 #
 
 # The triggers are set within the set_ftrace_filter file
-if [ ! -f set_ftrace_filter ]; then
-    echo "set_ftrace_filter not found? Is dynamic ftrace not set?"
-    exit_unsupported
-fi
+check_filter_file set_ftrace_filter
 
 do_reset() {
     reset_ftrace_filter

tools/testing/selftests/ftrace/test.d/ftrace/func_mod_trace.tc

···
 # SPDX-License-Identifier: GPL-2.0
 # description: ftrace - function trace on module
 
-[ ! -f set_ftrace_filter ] && exit_unsupported
+check_filter_file set_ftrace_filter
 
 : "mod: allows to filter a non exist function"
 echo 'non_exist_func:mod:non_exist_module' > set_ftrace_filter

tools/testing/selftests/ftrace/test.d/ftrace/func_profiler.tc

···
     exit_unsupported;
 fi
 
-if [ ! -f set_ftrace_filter ]; then
-    echo "set_ftrace_filter not found? Is dynamic ftrace not set?"
-    exit_unsupported
-fi
+check_filter_file set_ftrace_filter
 
 if [ ! -f function_profile_enabled ]; then
     echo "function_profile_enabled not found, function profiling enabled?"

tools/testing/selftests/ftrace/test.d/ftrace/func_set_ftrace_file.tc

···
 #
 
 # The triggers are set within the set_ftrace_filter file
-if [ ! -f set_ftrace_filter ]; then
-    echo "set_ftrace_filter not found? Is dynamic ftrace not set?"
-    exit_unsupported
-fi
+check_filter_file set_ftrace_filter
 
 fail() { # mesg
     echo $1

tools/testing/selftests/ftrace/test.d/ftrace/func_stack_tracer.tc

···
   exit_unsupported
 fi
 
+check_filter_file stack_trace_filter
+
 echo > stack_trace_filter
 echo 0 > stack_max_size
 echo 1 > /proc/sys/kernel/stack_tracer_enabled

tools/testing/selftests/ftrace/test.d/ftrace/func_traceonoff_triggers.tc

···
 #
 
 # The triggers are set within the set_ftrace_filter file
-if [ ! -f set_ftrace_filter ]; then
-    echo "set_ftrace_filter not found? Is dynamic ftrace not set?"
-    exit_unsupported
-fi
+check_filter_file set_ftrace_filter
 
 fail() { # mesg
     echo $1

tools/testing/selftests/ftrace/test.d/functions

···
+check_filter_file() { # check filter file introduced by dynamic ftrace
+    if [ ! -f "$1" ]; then
+        echo "$1 not found? Is dynamic ftrace not set?"
+        exit_unsupported
+    fi
+}
 
 clear_trace() { # reset trace output
     echo > trace

tools/testing/selftests/ftrace/test.d/kprobe/kprobe_ftrace.tc

···
 [ -f kprobe_events ] || exit_unsupported # this is configurable
 grep "function" available_tracers || exit_unsupported # this is configurable
 
+check_filter_file set_ftrace_filter
+
 # prepare
 echo nop > current_tracer
 echo _do_fork > set_ftrace_filter